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From Costin Manolache <>
Subject Re: Benchmarking gcj-built Tomcat
Date Thu, 16 Oct 2003 05:30:35 GMT
Gary Benson wrote:

> Hi all,
> I've been working on building Tomcat and its dependencies to native
> code with gcj, and I'm interested to see how it compares against
> Tomcat running under a 'normal' JVM.  Now, I'm well aware that
> benchmarks are not a real-world indicator of performance, but I don't
> have any particular web application to test and I was wondering if
> anyone has a benchmarking suite that they can point me at.

My benchmarks ( > 1 yr ago ) showed GCJ-based tomcat to be as fast as the
IBM JDK1.3 ( the fastest VM at that time ). There were small differences 
under different loads - but the garbage collector seemed like the biggest
factor ( GCJ performed worse on JSP pages where more objects were created
if I remember correctly ).

The amazing thing was the startup time - almost 0 ( it felt more like apache

BTW - GCJ is not a virtual machine and doesn't have a JIT -  it is a
ahead-of-time compiler, just like C and C++ compilers. My understanding is
that it compiles Java code to the same intermediary-code as C++ - so you
shouldn't see any major difference between C++ code and Java code compiled
with GCJ. 
Except that GCJ programs use garbage collection and java libraries - with
the good and the bads.

The biggest problem at that time was dynamic class loading. GCJ has a small
interpretor and could load servlets - but the difference in performance
between precompiled code and interpretor was significant. Another problem
was that not everything compiled, I had to do some tricks ( now it
shouldn't be a problem ). Also the tests were made with tomcat 3.3 - I
tried to compile 4.0 but there were more compile problems.


> In case you are interested in the gcj-built packages, they are
> available at as source rpms
> and as binary rpms compiled for Red Hat Linux 9.  Everything except
> the webapps is compiled to native code; the webapps are basically
> unmodified and are interpreted just as they would be with a normal JVM.
> Thanks,
> Gary
> [ ][ GnuPG 85A8F78B ][ ]

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